The short version of sublimation fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-09-20. Anything still debated is marked as such rather than presented as settled.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
Freezing determines ice crystal structure and pore size, which affect drying speed and product uniformity. Rapid freezing creates small crystals, while slow freezing creates larger crystals and often faster sublimation. During primary drying, chamber pressure is held below the vapor pressure of ice, and shelf temperature supplies heat for sublimation. The ice front recedes, leaving a porous matrix. Thermal limits such as collapse and eutectic temperatures set safe boundaries for formulation. These limits vary with solute composition and concentration.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
A typical cycle begins with freezing, sometimes including an annealing step to control ice crystal size. Freezing conditions influence the pore network that later allows vapor escape. During primary drying, shelf temperature and chamber pressure are set so heat enters the product while its temperature stays below the collapse or eutectic point. Secondary drying then raises the shelf temperature to desorb bound water and lower residual moisture. Cycle design depends on formulation, fill volume, container type, and equipment capability.
The physics of lyophilization couples heat transfer, mass transfer, and phase behavior. Sublimation requires a vapor pressure difference between the ice front and the chamber, and the dried layer adds resistance to vapor flow. Amorphous formulations are characterized by a glass transition temperature of the maximally freeze-concentrated solute, often denoted Tg'. Crystalline bulking agents can provide structure, while amorphous excipients stabilize labile components. Open questions remain about spatial heterogeneity, edge effects, and how laboratory cycles scale to production.
| Property | Value | Notes |
|---|---|---|
| Process name | Lyophilization or freeze-drying | Both terms appear in technical standards and literature. |
| Phase transition | Sublimation | Solid ice becomes vapor without a liquid step. |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product temperature and equipment. |
| Typical product temperature | -40 °C to -10 °C | Measured during primary drying; formulation sets limits. |
| Water content after drying | 0.5-3% w/w | Target varies by material and stability needs. |
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
A freeze-dryer consists of a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. Vials, ampoules, or bulk trays hold the product during the cycle. The condenser traps water vapor as ice at a temperature lower than the product. Cycle development balances shelf temperature, chamber pressure, and time. Scale-up can be difficult because heat and mass transfer change with equipment size, so process analytical tools and conservative validation are often used.
Lyophilization is a dehydration technique in which a product is frozen and the solvent is removed under reduced pressure. The low pressure allows ice to sublimate directly into vapor without passing through a bulk liquid phase. This differs from conventional drying, where heat drives evaporation and can damage heat-sensitive structures. The process is used for biological materials, pharmaceutical formulations, and some foods. Its main advantage is preservation of porous structure and rapid reconstitution.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
A descriptor which is applied to any substance or process which is being investigated for clinical use but either has not commenced, or has not completed, clinical trials. Examples: candidate vaccine, candidate formulation. Case report
== Research == Antibodies and antigens, produced in the Human Protein Atlas workflow, are used in research projects to study potential biomarkers in various diseases, such as breast cancer, prostate cancer, colon cancer, diabetes, autoimmune diseases, ovarian cancer and renal failure. Researchers involved with Human Protein Atlas projects, are sharing protocols and method details in an open-access group on protocols.io. A large effort is put into validating the antibody reagents used for profiling of tissues and cells, and the HPA has implemented stringent antibody validation criteria as suggested by the International Working Group for Antibody Validation (IWGAV).
=== Education === Kennedy opposed President Biden's student loan forgiveness plan, saying, "Americans who already paid off their debt, worked through college, went to a trade school, or chose to not go to school will pay off the loans that other people incurred. On what planet is that fair?" He celebrated the Supreme Court's ruling against loan forgiveness, writing, "Biden's attempt to cancel student debt was a woke injustice: Forcing Americans who paid their debt or chose not to go to school to foot bills for [people] who haven’t paid back their personal loans. SCOTUS made the right call. Hardworking Americans will be better off for it." Kennedy supports school choice and has argued that parents should get to pick the school their child attends, especially if their district is providing a poor education. He said, "We can't seem to teach our kids how to read and write and do basic math when we've got 18 years to do it. I don't understand that…I don't care what the political cost is. I'm willing to try just about anything to improve public elementary and secondary education, including vouchers, including school choice, including charter schools." In 2023, Kennedy encouraged the Louisiana legislature to pass HB 12, a bill that requires schools to give extra tutoring to students who cannot read at grade level by third grade. He has served as a volunteer substitute teacher in Louisiana schools for more than a decade. He told CNBC he volunteered at the schools because "It occurred to me that not many of the folks in that room really knew what public schools were like today".
These initially involved groups of soldiers that were inserted by helicopter, and were later expanded with paratroopers. The Rhodesian Light Infantry often provided the soldiers for fireforce teams. A key element of the Selous Scouts' methods was 'turning' captured insurgents to join the Rhodesian security forces. This was normally attempted shortly after insurgents were captured, with them being both threatened and offered incentives. The captured insurgent was usually approached by a former insurgent. In the resulting conversation, the former insurgent emphasised the hardships insurgents were experiencing and that those who were captured faced the death penalty under the Law and Order (Maintenance) Act. This legislation imposed severe penalties for people found to be members of subversive organisations, including the death penalty or long prison terms. The captured insurgent was also offered a lump sum payment as well as a soldier's salary if they agreed to fight for the Rhodesian government. If an insurgent agreed to be 'turned' and passed further vetting, they were assigned to a Selous Scout team and operated in regions in which they would not be recognised. Where possible, their family was housed on a Selous Scouts base. Only a small number of 'turned' insurgents ever deserted or betrayed the unit. Some of the prisoners captured by the Selous Scouts who refused to be 'turned' were killed. One of the tactics used by the Selous Scouts was to violate local customs while posing as insurgents with the goal of reducing support for the actual insurgents.
Sources: en.wikipedia.org
== Moisture == Many dry pharmaceuticals are sensitive to moisture. Tablets may become unstable and the drug may degrade. High barrier packaging (including seals) is necessary but, by itself, is often not enough. Shelf life of a moisture-sensitive drug can be extended by means of desiccants. Several types of dessicants are available; the type and quantity need to be matched to the particular drug and package. One common method is to include a small packet of dessicant in a bottle. Other methods of including desiccants attached to the inner surface or in the material have recently been developed.
=== Big molecules === Big molecules, also called high molecular weight (HMW) molecules, are mostly oligomers or polymers of small molecules, or chains of amino acids. Thus, within pharmaceutical sciences, peptides, proteins and oligonucleotides constitute the major categories. Peptides and proteins are oligomers or polycondensates of amino acids linked together by a carboxamide group. The threshold between the two is at about 50 amino acids. Because of their unique biological functions, a significant and growing part of new drug discovery and development is focused on this class of biomolecules. Their biological functions are determined by the exact arrangement or sequence of different amino acids in their makeup. For the synthesis of peptides, four categories of fine chemicals, commonly referred to as peptide building blocks (PBBs), are key: amino acids (=starting materials), protected amino acids, peptide fragments and peptides themselves. Along the way, the molecular weights increase from about 102 up to 104 and the unit prices from about $100 up to $105 per kilogram. However, only a small part of the total amino acid production is used for peptide synthesis. In fact, L-glutamic acid, L-methionine, L-aspartic acid and L-phenylalanine are used in large quantities as food and feed additives. About 50 peptide drugs are commercialized. The number of amino acids that make up a specific peptide varies widely. At the low end are the dipeptides.
=== Drug interactions === Amitriptyline/chlordiazepoxide should not be taken concomitantly with MAOIs, as doing so may cause high blood pressure and seizures . Like other benzodiazepines, concomitant use of amitriptyline/chlordiazepoxide with opioids increases the risk of drug-related mortality by way of profound sedation and respiratory depression.
== Medical uses == Alteplase is indicated for the treatment of acute ischemic stroke, acute myocardial infarction, acute massive pulmonary embolism, and blocked catheters. Similar to other thrombolytic drugs, alteplase is used to dissolve clots to restore tissue perfusion, but this can vary depending on the pathology. Generally, alteplase is delivered intravenously into the body. To treat blocked catheters, alteplase is administered directly into the catheter.
=== Floor realizations === After the player has completed all of the Abnormality battles on a floor, they can begin the floor's Realization: a multi-segmented puzzle battle against either Angela or Roland as they suffer from an emotional meltdown, taking after the floor's Abnormalities' appearances and abilities. Completing the Floor realization will grant E.G.O. pages exclusive to that floor. While not mandatory, only through completing all Floor realizations (sans the Kether floor) can the player unlock the game's true ending.
Sources: en.wikipedia.org
Insight – emphasis is on gaining a greater understanding of the motivations underlying one's thoughts and feelings (e.g. psychodynamic therapy) Action – focus is on making changes in how one thinks and acts (e.g. solution focused therapy, cognitive behavioral therapy) In-session – interventions center on the here-and-now interaction between client and therapist (e.g. humanistic therapy, Gestalt therapy) Out-session – a large portion of therapeutic work is intended to happen outside of session (e.g. bibliotherapy, rational emotive behavior therapy) The methods used are also different in regards to the population being served as well as the context and nature of the problem. Therapy will look very different between, say, a traumatized child, a depressed but high-functioning adult, a group of people recovering from substance dependence, and a ward of the state suffering from terrifying delusions. Other elements that play a critical role in the process of psychotherapy include the environment, culture, age, cognitive functioning, motivation, and duration (i.e. brief or long-term therapy).
Methocinnamox (MCAM) is an opioid receptor antagonist. It is a pseudo-irreversible non-competitive antagonist of the μ-opioid receptor and a competitive antagonist of the κ- and δ-opioid receptors. The drug has a very long duration of action of up to months with a single dose due to its pseudo-irreversibility. It is administered in animals by intravenous or subcutaneous injection. It was first described in the scientific literature in 2000. It has not been studied in humans as of 2022. There is interest in methocinnamox in the potential treatment of opioid use disorder and opioid overdose due to its much longer-lasting and insurmountable effects relative to other opioid antagonists like naloxone and naltrexone. Clinical trials of the drug are expected. Methocinnamox should not be confused with methoclocinnamox (MCCAM), which is a closely related but structurally different compound (chlorine instead of methyl on one of the benzene rings). The drug was derived via structural modification of buprenorphine.
He reprised his role as Kenobi in the 2022 miniseries Obi-Wan Kenobi, and won a Primetime Emmy Award for Outstanding Lead Actor for his portrayal of fashion designer Halston in the miniseries Halston (2021). McGregor also appeared in the motorcycle-travel documentary series Long Way Round, Long Way Down, Long Way Up, and Long Way Home alongside Charley Boorman. He starred in theatre productions of Guys and Dolls (2005–2007) and Othello (2007–2008). McGregor has been involved in charity work and has served as an ambassador for UNICEF UK since 2004.
==== Dependence and withdrawal ==== Drug tolerance develops rapidly in amphetamine abuse (i.e., recreational amphetamine use), so periods of extended abuse require increasingly larger doses of the drug in order to achieve the same effect. According to a Cochrane review on withdrawal in individuals who compulsively use amphetamine and methamphetamine, "when chronic heavy users abruptly discontinue amphetamine use, many report a time-limited withdrawal syndrome that occurs within 24 hours of their last dose." This review noted that withdrawal symptoms in chronic, high-dose users are frequent, occurring in roughly 88% of cases, and persist for 3–4 weeks with a marked "crash" phase occurring during the first week. Amphetamine withdrawal symptoms can include anxiety, drug craving, depressed mood, fatigue, increased appetite, increased movement or decreased movement, lack of motivation, sleeplessness or sleepiness, and lucid dreams. The review indicated that the severity of withdrawal symptoms is positively correlated with the age of the individual and the extent of their dependence. According to a 2025 review, the discontinuation of amphetamine at therapeutic doses does not typically result in withdrawal symptoms. Discontinuation of amphetamine may cause a recurrence of ADHD symptoms due to the cessation of treatment-related drug effects. In cases where mild withdrawal symptoms do occur, they can be avoided by tapering the dose.
=== Economic return === In 2000, the Joint Economic Committee of Congress reported NIH research, which was funded at $16 billion a year in 2000, that some econometric studies had given a rate of return of 25 to 40 percent per year by reducing the economic cost of illness in the US. It found that of the 21 drugs with the highest therapeutic impact on society introduced between 1965 and 1992, public funding was "instrumental" for 15. As of 2011, NIH-supported research helped to discover 153 new FDA-approved drugs, vaccines, and new indications for drugs in the 40 years prior. One study found NIH funding aided either directly or indirectly in developing the drugs or drug targets for all of the 210 FDA-approved drugs from 2010 to 2016. In 2015, Pierre Azoulay et al. estimated $10 million invested in research generated two to three new patents.
Sources: en.wikipedia.org
Conventional drying uses heat to evaporate liquid water, often at temperatures that can degrade sensitive materials. Lyophilization freezes the material first and then removes water by sublimation under vacuum. This avoids prolonged exposure to liquid water and high heat.
Lowering pressure reduces the boiling point of water and allows ice to sublimate at temperatures below freezing. Vacuum also limits convective heat transfer, so heat is usually supplied by shelves or radiation. The pressure must stay below the vapor pressure of ice at the product temperature.
The cycle typically includes freezing, primary drying, and secondary drying. Freezing solidifies water and sets the pore structure; primary drying removes bulk ice; secondary drying removes bound water. Some cycles add annealing or pre-freezing steps.
Freezing only converts liquid to solid. Lyophilization adds vacuum and controlled warming so frozen solvent sublimes, leaving a dry porous solid. The two steps are related but not interchangeable.